Brittygotchi

Well you could look into painting it an entirely different color but if you were going to do that, you should invest in some higher quality paint.

You could also use rubbing alcohol to rub off any paint on the shell already just to give yourself a "clean canvas"

As Hayden said, bedazzling is a popular way to customize tamas, and I know there is a video tutorial on bedazzling a tama somewhere on youtube.

If you are comfortable taking your tama apart or if you are feeling a little risky, you can change the paper background with a custom design of your own or even some glow-in-the-dark paper.

You might also be able to take off the star antenna fairly easily, in which case you could make a new antenna topper out of polymer clay and paint it over with some glaze to give it a more shiny look to match your tama.

I've seen someone say that they use nail polish pens to paint designs on their tamas and that the paint comes out nicely, so you could try that as well!

And once you're done with all the body work, you can make a cute beaded key chain to match

As you can see, the options are endless. Just decide how far you want to go with customizing and then go there!